ReSpect program

method

Specify the type of molecular Hamiltonian for SCF (and subsequent property) calculations.

Input block

Short variant

method: 
                                         
                                            
                                               
                                                
                                               
                                               
                                                  
                                                     
[hamiltonian]
                                                     
                                                  
                                               
                                                  
                                                
                                            
                                             
/
                                            
                                         
                                            
                                               
                                                
                                               
                                               
                                                  
                                               
                                                  
                                                     
[functional]

Default

none

Example

method: ks/b3lyp

method: ks-amfX2C/pbe0

method: mdks/cam-b3lyp

Note

The explicit definition of [functional] is mandatory for Kohn–Sham-type [hamiltonian]s.

geometry

Specify the molecular geometry.

Input block

Extended variant

geometry:

[element-symbol] [x] [y] [z]

Default

none

Example

#water in the xyz format
geometry:
   H  -0.756690  +0.466877  0.000000 
   H  +0.756690  +0.466877  0.000000 
   O  +0.000000  -0.119015  0.000000

#ethylene in the z-matrix format
geometry:
   H
   C  1  1.08
   H  2  1.08  1  120.0
   C  2  1.40  3  120.0  1  180.0
   H  4  1.08  2  120.0  1  180.0
   H  4  1.08  2  120.0  1  0.000

Note

Angstroms are used as default units for geometry.

The geometry can be provided either in the Cartesian (xyz) format or in the Z-matrix format.

Tip

The default units can be changed by the keyword "geo-units".

basis

Specify atomic orbital basis sets.

Input block

Short variant

basis: 
                                         
                                            
[basis-name]

Extended variant

basis:

all             : [basis-name]

[element-index] : [basis-name]

[element-symbol]: [basis-name]

Default

none

Example

In this example, the orbital basis "ucc-pvdz" is assigned to all elements.

basis: ucc-pvdz

In this example, the orbital basis "upc-1" is assigned first to all elements. Then, the basis is replaced by "ucc-pvdz" for the 4th element (as specified in the input block "geometry") and "dyall-vdz" for all bromine atoms.

basis:
   all : upc-1 
   4   : ucc-pvdz
   Br  : dyall-vdz

Note

In relativistic calculations the orbital basis must be in an uncontracted form. All basis sets from the internal program library are of this form.

Tip

The complete list of available [basis-name]s can be found here.

auxbas

Specify atomic auxiliary basis sets.

Input block

Short variant

auxbas: 
                                         
                                            
[basis-name]

Extended variant

auxbas:

all             : [basis-name]

[element-index] : [basis-name]

[element-symbol]: [basis-name]

Default

none

Example

In this example, the auxiliary basis "ucc-pvtz" is assigned to all elements.

auxbas: ucc-pvtz

In this example, the auxiliary basis "upc-1" is assigned first to all elements. Then, the basis is replaced by "ucc-pvdz" for the 4th element (as specified in the input block "geometry") and "dyall-vdz" for all bromine atoms.

auxbas:
   all : upc-1 
   4   : ucc-pvdz
   Br  : dyall-vdz

Note

The use of auxiliary basis makes sense only in connection with an approximative evaluation of electron repulsion integrals (ERI) by means of the resolution-of-identity (RI) technique. This is controled by the keyword "acceleration" in the "eri" block.

The names of matching orbital and auxiliary basis sets are identical. Therefore, one can omit the definition of auxiliary basis, provided the orbital basis was selected from the internal program library. In this case, the program will assign the auxiliary basis automatically.

xc

Specify details associated with the evaluation of the exchange–correlation potential.

Input block

Extended variant

xc:

hfx: [integer]

class: [string]

threshold: [real]

noncollinearity: [string]

regularization-cutoff: [real]

Default

xc:
   noncollinearity: v2005
   regularization-cutoff: 1.e-30
   threshold: 1.e-10

Example

xc:
  noncollinearity: v2005
  regularization-cutoff: 1.0e-15

xc:
  hfx: 50

Note

In the case of open-shell systems the noncollinearity option is automatically transferred to the property calculation, therefore its repeating specification in the xc block of the respective property section is optional.

Warning

In the case of closed-shell systems (multiplicity = 1) every noncollinearity option leads to the same noncollinear scheme for the xc potential. Therefore, when noncollinearity option is specified by the user the program will stop. The type of the noncollinearity scheme for the xc kernel of closed-shell systems may be set in the block xc of the respective property section.

eri

Specify details associated with the evaluation of electron repulsion integrals (ERI) and related two-electron Fock contributions.

Input block

Short variant

Extended variant

eri:

class: [string]

threshold: [real]

acceleration: [string]

Default

eri:
   class:        llll
   threshold:    1.e-10
   acceleration: none

Example

eri: ri-j

eri:
   class:        ssss/abcd 
   threshold:    1.e-15
   acceleration: ri-j

grid

Specify atomic grids for the numerical evaluation of exchange-correlation DFT contributions.

Input block

Short variant

Extended variant

grid:

all: [string]

[element-symbol]: [string]

[element-index]: [string]

...

Default

grid: adaptive

Example

grid: large

grid:
     C: medium
     7: large

Note

There can be multiple instances of [element-symbol] and [element-index] in the grid block.

While lines in the grid block can be mixed, they are always processed in the following order: "all", "element-symbol", and "element-index" keywords.

The order of processing the data matters, since the latter lines rewrite the data of the former lines. This way one can easily set the same grid for all carbons except the carbon number 7 (see example).

initmo

Provide starting/initial molecular orbitals for SCF calculations.

Input line

Default

initmo: atomic

Example

initmo: eht

charge

Specify the total molecular charge.

Input line

Default

charge: 0

Example

charge: -2

multiplicity

Specify the spin multiplicity.

Input line

multiplicity:
                               
                                  
[integer]

Default

multiplicity: 1  #singlet

Example

multiplicity: 3  #triplet

convergence

Specify the convergence threshold for SCF iterations.

Input line

convergence:
                               
                                  
[real]

Default

convergence: 1.0e-06

Example

convergence: 2.5e-5

Tip

We recommend to set the threshold value to ~1.0e-4 in cases when a loose SCF convergence is sufficient, such as in initial guess calculations, etc. For productive runs, however, the thresholds setup within the range 1.0e-5—1.0e-6 is advised. Tight convergence in the SCF is considered for thresholds below 1.0e-7.

maxiterations

Specify the maximum number of SCF iterations.

Input line

maxiterations:
                               
                                  
[integer]

Default

maxiterations: 30

Example

maxiterations: 25

nc-model

Specify the nuclear charge distribution model.

Input line

Default

nc-model: point

Example

nc-model: gauss

Note

Since the relativistic wave function exhibits a singularity at nuclear centers, users are advised to use a finite-size nuclear charge model such as "gauss" model.

cscale

Scale the speed of light by a factor.

Input line

Default

cscale: 1.0

Example

cscale: 20.0

Note

The scaling factor should be a positive real number. By setting cscale < 1.0, the speed of light decreases and molecular systems turn into a hyper-relativistic regime where all relativistic terms become amplified. On the other hand, by setting cscale > 1.0 the speed of light increases and molecular systems approach their non-relativistic limit.

Warning

Due to numerical reasons, the users are advised to set the cscale parameter within the limits: 0.1 < cscale < 50.0.

1esoscale

Scale the one-electron spin-orbit interaction by a factor.

Input line

Default

1esoscale: 1.0

Example

1esoscale: 0.0

Note

The scaling factor should be a positive real number. By setting 1esoscale = 0.0, one can switch off the one-electron spin-orbit interaction completely.

Warning

Due to numerical reasons, the users are advised to set the 1esoscale parameter within the limits: 0.0 < 1esoscale < 1.0.

checkpoint

Specify the frequency of data checkpointing during SCF iterations.

Input line

checkpoint:
                               
                                  
[integer]

Default

checkpoint: 10

Example

checkpoint: 2

Tip

The importance of more frequent checkpointing -- storing intermediate SCF data to disk for the later reuse as a restart -- increases with the system size.

spin

Control the initial orientation of spin polarization in relativistic SCF calculations.

Input line

Default

spin: z

Example

spin: x

Note

This keyword plays an important role only in relativistic Kramers-unrestricted calculations of open-shell molecules, in particular in connections with the EPR property calculations, as it controls the initial orientation of the spin polarization. In non-relativistic regime, however, the keyword does not make a sense and is therefore ignored.

geo-units

Specify units in which the molecular geometry is provided.

Input line

geo-units:
                               
                                  
[string]

Default

geo-units: angstrom

Example

geo-units: bohr

mo-analysis

Specify the type of molecular orbitals analysis.

Input line

mo-analysis:
                               
                                  
[string]

Default

none

Example

mo-analysis: mulliken

Warning

So far, the keyword works only for the non-relativistic type of Hamiltonians.

[string]	description
eht	extended Hueckel's theory
bare	one-electron (bare nucleus) Hamiltonian
atomic	superposition of atomic densities

[string]	description
point	point nuclear charge distribution model
gauss	gaussian nuclear charge distribution model

[string]	description
x	initial spin polarization along the x-coordinate
y	initial spin polarization along the y-coordinate
z	initial spin polarization along the z-coordinate

[string]	description
angstrom
bohr

[string]	description
basic
mulliken

[hamiltonian]	description
ks	nonrelativistic one-component Kohn–Sham Hamiltonian
hf	nonrelativistic one-component Hartree–Fock Hamiltonian
ks-1eX2C	relativistic two-component Kohn–Sham Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian
hf-1eX2C	relativistic two-component Hartree–Fock Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian
ks-amfX2C	relativistic two-component Kohn–Sham Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian corrected by superposed 4c atomic two-electron interactions
hf-amfX2C	relativistic two-component Hartree–Fock Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian corrected by superposed 4c atomic two-electron interactions
ks-eamfX2C	relativistic two-component Kohn–Sham Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian corrected by 4c molecular two-electron interactions that arise from superposed atomic density
hf-eamfX2C	relativistic two-component Hartree–Fock Hamiltonian based on the exact two-component (X2C) transformation of the parent 4c molecular one-electron Dirac Hamiltonian corrected by 4c molecular two-electron interactions that arise from superposed atomic density
ks-mmfX2C	relativistic two-component Kohn–Sham Hamiltonian based on the post-SCF exact two-component (X2C) transformation of the converged 4c molecular (mean-field) Hamiltonian
hf-mmfX2C	relativistic two-component Hartree–Fock Hamiltonian based on the post-SCF exact two-component (X2C) transformation of the converged 4c molecular (mean-field) Hamiltonian
mdks	relativistic four-component Dirac–Kohn–Sham Hamiltonian
mdhf	relativistic four-component Dirac–Hartree–Fock Hamiltonian

[functional]	description
slaterx	Slater local exchange DFT functional J. C. Slater, Phys. Rev. 81, 385–390 (1951)
svwn5	Slater local exchange and Vosko–Wilk–Nusair local correlation DFT functional (LDA-type) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
bp86	Becke non-local exchange and Perdew non-local correlation DFT functional (GGA-type) A. D. Becke, Phys. Rev. A 38, 3098–3100 (1988) J. P. Perdew, Phys. Rev. B 33, 8822–8824 (1986) Erratum, Phys. Rev. B 34, 7406–7406 (1986) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
pp86	Perdew–Wang non-local exchange and correlation DFT functional (GGA-type) J. P. Perdew, Phys. Rev. B 33, 8822–8824 (1986) Erratum, Phys. Rev. B 34, 7406–7406 (1986) J. P. Perdew, and Y. Wang, Phys. Rev. B 33, 8800–8802 (1986) Erratum, Phys. Rev. B 40, 3399–3399 (1989) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
kt2	Keal–Tozer non-local exchange and Vosko–Wilk–Nusair correlation DFT functional (GGA-type) T. W. Keal, and D. J. Tozer, J. Chem. Phys. 119, 3015 (2003) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
blyp	Becke non-local exchange and Lee–Yang–Parr correlation DFT functional (GGA-type) A. D. Becke, Phys. Rev. A 38, 3098–3100 (1988) C. Lee, W. Yang, and R. G. Parr, Phys. Rev. B 37, 785–789 (1988) J. C. Slater, Phys. Rev. 81, 385–390 (1951)
pbe	Perdew–Burke–Ernzerhof exchange and correlation DFT functional (GGA-type) J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865–3868 (1996) Erratum, Phys. Rev. Lett. 78, 1396–1396 (1997) J. C. Slater, Phys. Rev. 81, 385–390 (1951)
b3lyp	Becke three-parameters exchange and Lee–Yang–Parr correlation DFT functional (hybrid-type) A. D. Becke, Phys. Rev. A 38, 3098–3100 (1988) C. Lee, W. Yang, and R. G. Parr, Phys. Rev. B 37, 785–789 (1988) P. J. Stephens, F. J. Devlin, C. F. Chabalowski, and M. J. Frisch, J. Phys. Chem. 98, 11623–11627 (1994) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
pbe0	Perdew–Burke–Ernzerhof exchange and correlation DFT functional (hybrid-type) J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865–3868 (1996) Erratum, Phys. Rev. Lett. 78, 1396–1396 (1997) C. Adamo, and V. Barone, J. Chem. Phys. 110, 6158–6170 (1999) J. C. Slater, Phys. Rev. 81, 385–390 (1951)
lc-svwn5	Long-range corrected Slater local exchange and Vosko–Wilk–Nusair local correlation DFT functional (range-seperated LDA-type) H. Iikura, T. Tsuneda, T. Yanai, K. Hirao, J. Chem. Phys. 115, 3540 (2001) A. Savin, in Recent Advances in Density Functional Methods, Part I , 129 (1995) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)
lc-blyp	Long-range corrected Becke non-local exchange and Lee–Yang–Parr correlation DFT functional (range-separated GGA-type) H. Iikura, T. Tsuneda, T. Yanai, K. Hirao, J. Chem. Phys. 115, 3540 (2001) A. Savin, in Recent Advances in Density Functional Methods, Part I , 129 (1995) A. D. Becke, Phys. Rev. A 38, 3098–3100 (1988) C. Lee, W. Yang, and R. G. Parr, Phys. Rev. B 37, 785–789 (1988) J. C. Slater, Phys. Rev. 81, 385–390 (1951)
cam-b3lyp	Range-separated Becke three-parameters exchange and Lee–Yang–Parr correlation DFT functional (range-separated hybrid-type) T. Yanai, D. P. Tew, N. C. Handy, Chem. Phys. Lett. 393, 51 (2004) H. Iikura, T. Tsuneda, T. Yanai, K. Hirao, J. Chem. Phys. 115, 3540 (2001) A. Savin, in Recent Advances in Density Functional Methods, Part I , 129 (1995) A. D. Becke, Phys. Rev. A 38, 3098–3100 (1988) C. Lee, W. Yang, and R. G. Parr, Phys. Rev. B 37, 785–789 (1988) P. J. Stephens, F. J. Devlin, C. F. Chabalowski, and M. J. Frisch, J. Phys. Chem. 98, 11623–11627 (1994) J. C. Slater, Phys. Rev. 81, 385–390 (1951) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys. 58, 1200–1211 (1980)

[string]	description
v2005	The 2005 version of the noncollinear xc scheme was for the first time used in the ReSpect for the calculation of g-tensor at two- [Malkin2005] and four-component [Repisky2010] level of theory. The implementation details of the noncollinear xc energy and potential can be found in reference ReSpect article [Repisky2020] in eqs (63) and (68), respectively. This version of the noncollinear scheme was used in all ReSpect calculations until 2019 whenever spin-orbit effects have been included variationally. In particular, the noncollinear xc potential was used in evaluation of scf procedure and subsequent calculation of EPR (gt and hfcc) or paramagnetic NMR parameters (cs and sscc). The 2005 version of the noncollinear scheme is not suitable for frequency-dependent response property calculations (tddft and cpp), which is its most notable disadvantage. I. Malkin, O. L. Malkina, V. G. Malkin, and M. Kaupp, J. Chem. Phys. 123, 244103 (2005) S. Komorovsky, M. Repisky, O. L. Malkina, V. G. Malkin, I. Malkin-Ondik, and M. Kaupp, J. Chem. Phys. 128, 104101 (2008) M. Repisky, S. Komorovsky, E. Malkin, O. L. Malkina, and V. G. Malkin, Chem. Phys. Lett. 488, 94–97 (2010) M. Repisky, S. Komorovsky, M. Kadek, L. Konecny, U. Ekstrom, E. Malkin, M. Kaupp, K. Ruud, O. L. Malkina, and V. G. Malkin, J. Chem. Phys. 152, 184101 (2020)
v2019	The 2019 version of the noncollinear xc potential have been published in the framework of LR-TDDFT [Komorovsky2019]. This is the most general formulation of the noncollinear scheme and can be used for prediction of all spectroscopic parameters available in the ReSpect. The noncollinear xc potential is formulated in the analytic form. The implementation details of the 2019 version of the noncollinear xc energy and potential are summarized in ref [Komorovsky2019] in eq (16) and Table I, respectively. In the output files we refer to this formulation of the noncollinear xc scheme as WSK2019 ([Wullen2002] + [Scalmani2012] + [Komorovsky2019]). C. Van Wüllen, J. Comput. Chem. 23, 779–785 (2002) G. Scalmani and M. J. Frisch, J. Chem. Theory Comput. 8, 2193–2196 (2012) S. Komorovsky, P. Cherry, and M. Repisky, J. Chem. Phys. 151, 184111 (2019)

[string]	description
llll	evaluate only the Omega(LLLL) class (default for one- and two-component Hamiltonians)
ssss	evaluate exactly all Omega(LLLL), Omega(LLSS), Omega(SSLL), and Omega(SSSS) classes (default for four-component Hamiltonians)

[string]	description
llll	evaluate only the [LL\|LL] class (default for one- and two-component Hamiltonians)
ssll/abcd	evaluate exactly [LL\|LL], [LL\|SS] and [SS\|LL] classes but neglect [SS\|SS]
ssss/aabb	evaluate exactly [LL\|LL], [LL\|SS] and [SS\|LL] classes and use an one-center approximation for [SS\|SS]. In this approximation, both functions in [SS\| and \|SS] should share the same atomic center, otherwise they are excluded from evaluation. This is the default for four-component Hamiltonians.
ssss/abcd	evaluate exactly all four ERI classes

[string]	description
c4	complex algebra over 4Nx4N matrices
h2	quaternion algebra over 2Nx2N matrices

[string]	description
ri-j	resolution-of-identity (RI) for the two-electron Coulomb term
none	no approximation imposed

[eri]	description
ri-j	resolution-of-identity (RI) for the two-electron Coulomb term
exact	exact evaluation of four-center two-electron integrals

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

[string]	description
coarse	Adaptive angular part with a fixed radial number of points calculated as 30 + (10*p), where p is the period number of the defined element.
medium	Adaptive angular part with a fixed radial number of points calculated as 40 + (10*p), where p is the period number of the defined element.
large	Adaptive angular part with a fixed radial number of points calculated as 50 + (10*p), where p is the period number of the defined element.
adaptive	Adaptive grid in both the radial and angular part calculated from the input basis.

Latest Posts

Webpage update

July 17, 2024

Program update: ReSpect 5.3.0

July, 2024

Latest Publications

Book chapter on relativistic real-time electron dynamics

May, 2024

Book chapter on relativistic theory of EPR and (p)NMR

May, 2024

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Hylleraas Centre
Department of Chemistry
UiT The Arctic University of Norway
Tromsø, NO-9037 Norway
Email: info@respectprogram.eu